An implant and particularly a bone implant include a portion or section or end which is adapted to be firstly introduced into a body during an implantation. Such a portion or section or end is usually referred to as leading portion or leading section or leading end. Consequently, an opposite portion or section or end of the implant is adapted to be finally introduced, wherein this portion or section or end may additionally be configured for an engagement of a tool for inserting the implant into the body. Such a portion or section or end is usually referred to as trailing portion or trailing section or trailing end.
A bone implant may be a pin or a nail or screw. A bone nail may be an intramedullary nail, for example a femur nail, a humerus nail or a tibia nail. A bone screw may be a screw for fixing fragments of a bone fracture or may be a locking screw for locking a bone nail in the bone.
However, due to the anatomical variation of bones it may happen that the trailing end of a bone implant sticks out of a bone after implant placement. The trailing end of the implant may act as an interface towards a target or aiming device. In order to create a solid fixation nails may be provided with grooves in order to fit pegs on the post of the target device for accurate alignment, for sufficient fixation, and for controlling the forces applied during implant insertion and removal.
It may occur that patients complain about pain after surgery in this area, especially when the implant is sticking out of the bone. This pain may be caused by sharp edges at the trailing end of the implant. Such edges may cause irritations and/or injuries of the surrounding soft tissue.
On the other hand, the trailing end of a bone nail may be arranged within a bone, i.e. under a bone surface, after an implantation. In such case, bone tissue may grow over the trailing edges of the bone nail resulting in difficulties to explant the bone nail after healing of a treated bone fracture.
To reduce these problems, an end cap in form of a small screw may be inserted into the trailing end of the implant, with the screw having a screw head with a length and smooth and rounded edges.
However, it may be difficult to align the screw axis to an axis of an inner thread in the trailing end of the implant when introducing such a small screw into an implant which is already inserted into a bone and an axis of which is thus not clearly recognizable, i.e. visible, as can be seen in FIG. 9. Consequently, a small screw as an end cap may easily tilt during insertion.